1. Field of the Invention
The present invention relates to a method for detecting and locating water-producing zones and/or water thief zones in a subterranean formation penetrated by a well bore. More specifically, the invention is directed to a method for detecting and locating such water-producing zones and/or water thief zones in subterranean hydrocarbon-containing formations employing radioactive injection techniques in combination with radioactive well logging techniques wherein the material being injected into the formation is an aqueous solution containing an irradiated water soluble compound, said compound having preferential silica adsorptive characteristics.
2. Brief Description of the Prior Art
In the production of hydrocarbon from a subterranean formation one often encounters excessive water production resulting from high water producing zones in the formation or, when employing secondary recovery techniques, water thief zones in the subterranean formation. In order to achieve the desirable production of the hydrocarbon from the formation, whether the same be primary production or secondary recovery production, one must identify and locate the water producing zones and/or water thief zones in the formation so that such zones can be remedially treated to substantially eliminate excess water production, or water losses.
In the past, various methods have been proposed such as the use of radioactive tracers to follow movement of gas, oil, and water in such subterranean formations. Such prior art methods have utilized many different materials such as dyes, chemical compounds, helium, carbon monoxide, and radioactive isotopes. In addition, many of such prior art methods have employed compounds involving expensive equipment, excessive shut down procedures and highly specialized equipment. Further, care must be exercised to prevent over-contamination of the formation which results in long periods of inactivity of the formation. Many of the prior art techniques have employed the use of compositions which tend to alter the permeability characteristics of the formation. Thus, the oil industry has long sought an economical, simple method to detect and locate water producing zones and/or water thief zones in subterranean hydrocarbon bearing formations.